1. Field of the Invention
The present invention relates to a plasma system using the remote plasma method of separation of the plasma and substrate. More particularly, this invention relates to a plasma system for performing uniform plasma CVD or plasma etching on a large area substrate.
2. Description of the Related Art
As a method of plasma treatment which reduces the damage caused by the plasma, there is known the remote plasma method. When this remote plasma method is applied to plasma CVD, the plasma generation chamber and the film deposition chamber are separated, a source gas is decomposed by the plasma near the interface between the two, and the reaction product produced at that time is deposited on a substrate placed in the film deposition chamber. By isolating the substrate from the plasma in this way, it is possible to lessen the damage to the substrate caused, mainly, by the charged particles in the plasma.
As a structure for separating the plasma generation chamber and the substrate treatment chamber, there is known, for example, an electron cyclotron resonance (ECR) plasma treatment apparatus such as is disclosed in Japanese Unexamined Published Patent Application No. 1-168027. In this apparatus, in the plasma generation chamber, the cyclotron angular frequency w.sub.c of the electrons engaged in cycloid motion due to the Lawrence force in the magnetic field and the angular frequency w of the microwave field are made to match (to establish ECR conditions) and the microwave energy is made to be absorbed resonantly in the electrons to cause the production of ECR plasma. At that time, an antimagnetic effect appears due to the cyclotron resonance circular motion of the high energy electrons and a plasma flow is formed in the weak magnetic field direction due to the interaction with the dispersed magnetic field, so the substrate treatment chamber is provided in the weak magnetic field direction and ECR plasma treatment is performed on the substrate placed in the same.
In a conventional CVD apparatus based on the remote plasma method, however, generally the plasma generation chamber is small and, further, there is only one location where the source gas for the film formation can be broken down. Therefore, it was considered difficult to form a uniform film on a large area wafer such as one having an 8 inch diameter or a 12 inch diameter.
On the other hand, in the ECR plasma treatment apparatus described in the above publication, the openings in the source gas introduction system were located both near the leadout plate of the plasma and near the substrate so as to try to achieve uniform plasma treatment. The ECR plasma generated at the plasma generation chamber, however, was led out to the substrate treatment chamber along the dispersed magnetic field, and the ECR plasma acted directly on the substrate, so damage due to irradiation of the substrate by the ECR plasma could not be avoided.